#![no_std]
#[macro_use]
extern crate alloc;

use alloc::vec::Vec;
use cryptography::hashing::checksum;
use process::PID;
use versioning::Version;

pub const VERSION: Version = Version::new(0, 1, 0);

#[repr(C)]
pub struct Message {
    src: PID,         // bytes 0-3
    dest: PID,        // bytes 4-7
    version: Version, // bytes 8-10
    checksum: u64,    // bytes 11-19
    length: usize,    // bytes 20-23
    timestamp: u64,   // bytes 24-31

    body: Vec<u8>,
}
impl Message {
    pub fn set_checksum(&mut self) {
        self.checksum = self.compute_body_checksum()
    }

    fn compute_body_checksum(&mut self) -> u64 {
        checksum(&self.body)
    }
}

#[test]
fn test_checksum() {
    let mut message = Message {
        src: 123,
        dest: 456,
        version: Version::new(0, 1, 0),
        checksum: 0,
        timestamp: 0,
        length: 5,
        body: vec![1, 2],
    };

    message.set_checksum();

    assert_eq!(message.checksum, 3);
    assert_ne!(message.checksum, 1)
}